1. Field of the Invention
The present invention relates to a fruit or vegetable product harvesting apparatus and a fruit or vegetable product harvesting method.
2. Description of the Related Art
The economic value of a harvesting target of fruits and vegetables depends on the content of a specific ingredient contained in the harvesting target. For example, an oil palm bunch (fresh fruit bunch) includes a large number of (e.g., 1,000 to 3,000) fruits, each of which includes pericarp (also referred to as “pulp”), mesocarp and a seed (also referred to as “palm kernel”). In the case where the harvesting target is an oil palm bunch, the content of oil in the mesocarp or palm kernel in a fruit is considered important. The oil contained in the mesocarp is generally called “palm oil”, and the oil contained in the palm kernel is generally called “palm kernel oil”. The content of oil in the oil palm fruit is known to be different in accordance with the maturity level of the oil palm bunch (specifically, fruits). Specifically, the oil content in a ripe fruit is known to be higher than the oil content in an unripe, underripe (slightly unripe) or overripe fruit. For example, the oil content in a fruit when being ripe is about three times the oil content therein when being unripe.
For example, in Malaysia, the Malaysian Palm Oil Board (MPOB) has established guidelines on the maturity level of fruits. Currently, harvesting workers working in oil palm plantations subjectively determine whether or not to harvest the fruits in accordance with the guidelines. As described above, the maturity level of the oil palm bunch significantly influences the yield of oil. Therefore, a wrong subjective determination of a harvesting worker (human error) on whether or not to harvest the fruits may have a significant influence on the yield. In actuality, it is difficult for a harvesting worker to correctly determine whether the fruits are ripe or underripe, which is a factor that decreases the yield of oil.
In such a situation, measurement devices have been developed for measuring various characteristics of an oil palm bunch, which is a subject (harvesting target), by use of near infrared light without destroying the oil palm bunch, namely, in a nondestructive manner. Such measurement devices irradiate the subject with near infrared light of a predetermined wavelength and measure a characteristic to be measured based on the reflectance of the light from the subject.
WO2012/074372 discloses a system that determines the maturity level of oil palm fruits using a hyperspectral imaging technology. WO2012/074372 also discloses the characteristic that the reflectance of the light of the near infrared wavelength band varies in accordance with the maturity level of the fruit. In this system, an image of a harvested oil palm bunch is captured by a spectral camera to acquire a sample image, and the sample image is analyzed based on the characteristic that the reflectance varies in accordance with the maturity level of the fruit to determine the maturity level of the oil palm fruit.
Japanese Laid-Open Patent Publication No. 2000-356591 discloses a nondestructive sugar content meter that calculates the sugar content of fruits and vegetables by a sugar content estimation equation by use of an output from a photoelectric conversion element based on light that has passed a near infrared light wavelength filter. Japanese Laid-Open Patent Publication No. Hei 8-122250 discloses a nondestructive measurement device that determines the maturity level of fruits and vegetables based on the intensity ratio between two specific wavelength components of near infrared light.